I'd have liked to be able to say my favorite Alliance Racial Leader was Tyrande.
She's the Night Elf after all and I love the concept of her, this strong female leader for the Night Elves, who is also a strategist and a military force. But for what little I've actually seen of her in action in game I don't feel like she lives up to the concept at all. It saddens me, though while thinking about it today I came up with a theory regarding the 'A Little Patience' Scenario that is my new head canon.
But Tyrande still doesn't get to be my favorite Alliance Leader. At least not until they give her more of a role that lives up to what she should be in game. Still I love the concept of her, so she's my second favorite.
And though this is silly and a little off topic: I really hate her new hairstyle.
But who is my favorite. I went through all of them and the little I know about them mostly what I've seen in game and I finally decided that it's Genn Greymane.
Mostly because of what I saw of him in the Worgen starting area. He's a king without a kingdom currently, his people are all cursed and he's been through a lot. He's made some mistakes, but in general I think he's always been trying to do what he thought was best for his own people. Besides, Worgen are pretty neat. So Genn Greymane's my favorite Alliance Leader, though I can't think of any of the Alliance Leaders that I actively dislike the way I do with a few of the Horde Leaders.